Arrowhead Butterweed
Senecio triangularis
Arrowhead Butterweed (Senecio triangularis) is a native perennial herb that grows in northern, southern and central California. It is moderately fast growing and long-lived. It grows in an upright form to a height of 4 feet, with active growth during the summer and fall. Flowers are yellow and striking, and bloom in the mid summer. Leaves are medium green and deciduous. It tends to grow in wet meadows and streambanks in open places, at elevations from 4000-11000 feet.
Calscape
https://calscape.org/loc-California/Butterweed,%20Arrowhead%20(Senecio%20triangularis)